Improve macros.js test coverage and fixed module export in macros.js

[stutijain2006]

This PR improves the test case coverages of macros.js and fixes an issue with how functions were being imported.

Test Cases Added-

1. Edge Test case for blockIsMacro to test the behavior when a block exists in protoBlockDict but has no macroFunc and when a custom block has macroFunc even if it is not part of the built-in list.
2. Override behavior Test for getMicroExpansion which verifies that a protoBlock with macroFunc correctly overrides built-in macro definities.
3. Coordinate propagation Test to verify that built-in macros correctly use the provided x and y coordinates in their expansion.

Module Export Issue-
Previously macros.js exported functions like this:

module.exports = blockIsMacro;
module.exports = getMacroExpansion;

the second line overwrites the first export, making only getMacroExpansion accessible.

Now, both functions are exported properly:
module.exports = { blockIsMacro, getMacroExpansion };
and the import in tests was updated to
const { blockIsMacro, getMacroExpansion } = require("../macros");

After these additions-

1. 100% statement coverage
2. 100% function coverage
3. 93.75% branch coverage
4. All tests passing
   This ensures macros.js is now fully tested and more robust against edge cases.

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.

[vanshika2720]

@stutijain2006 please pull the latest master, rebase it into your branch, and push again.

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.